Given a list of scalars or reference variables, writes out their contents
in perl syntax. The references can also be objects. The contents of each
variable is output in a single Perl statement. Handles self-referential
structures correctly.

The return value can be evaled to get back an identical copy of the original reference structure.

Any references that are the same as one of those passed in will be named
$VARn (where n is a numeric suffix), and other duplicate references to substructures
within $VARn will be appropriately labeled using arrow notation. You can specify names
for individual values to be dumped if you use the Dump() method, or you can change the default $VAR prefix to something else. See $Data::Dumper::Varname and $Data::Dumper::Terse
below.

The default output of self-referential structures can be evaled, but the nested references to $VARn will be undefined, since a recursive structure cannot be constructed using
one Perl statement. You should set the
Purity flag to 1 to get additional statements that will correctly fill in these
references.

In the extended usage form, the references to be dumped can be given
user-specified names. If a name begins with a *, the output will describe the dereferenced type of the supplied reference
for hashes and arrays, and coderefs. Output of names will be avoided where
possible if the Terse flag is set.

In many cases, methods that are used to set the internal state of the
object will return the object itself, so method calls can be conveniently
chained together.

Returns a newly created Data::Dumper object. The first argument is an anonymous array of values to be dumped.
The optional second argument is an anonymous array of names for the values.
The names need not have a leading
$ sign, and must be comprised of alphanumeric characters. You can begin a
name with a * to specify that the dereferenced type must be dumped instead of the reference itself, for
ARRAY and
HASH references.

The prefix specified by $Data::Dumper::Varname will be used with a numeric suffix if the name for a value is undefined.

Data::Dumper will catalog all references encountered while dumping the
values. Cross-references (in the form of names of substructures in perl
syntax) will be inserted at all possible points, preserving any structural
interdependencies in the original set of values. Structure traversal is
depth-first, and proceeds in order from the first supplied value to the
last.

Returns the stringified form of the values stored in the object (preserving
the order in which they were supplied to new), subject to the configuration options below. In an array context, it
returns a list of strings corresponding to the supplied values.

The second form, for convenience, simply calls the new method on its arguments before dumping the object immediately.

This method is available if you were able to compile and install the
XSUB extension to Data::Dumper. It is exactly identical to the Dump method above, only about 4 to 5 times faster, since it is written entirely in
C.

Queries or adds to the internal table of already encountered references.
You must use Reset to explicitly clear the table if needed. Such references are not dumped;
instead, their names are inserted wherever they are encountered
subsequently. This is useful especially for properly dumping subroutine
references.

Expects a anonymous hash of name => value pairs. Same rules apply for
names as in new. If no argument is supplied, will return the ``seen'' list of name =>
value pairs, in an array context. Otherwise, returns the object itself.

Returns the stringified form of the values in the list, subject to the
configuration options below. The values will be named $VARn in the output, where n is a numeric suffix. Will return a list of strings in an array context.

Several configuration variables can be used to control the kind of output
generated when using the procedural interface. These variables are usually
localized in a block so that other parts of the code are not affected by the
change.

These variables determine the default state of the object created by
calling the new method, but cannot be used to alter the state of the object thereafter. The
equivalent method names should be used instead to query or set the internal
state of the object.

The method forms return the object itself when called with arguments, so
that they can be chained together nicely.

Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0
spews output without any newlines, indentation, or spaces between list
items. It is the most compact format possible that can still be called
valid perl. Style 1 outputs a readable form with newlines but no fancy
indentation (each level in the structure is simply indented by a fixed
amount of whitespace). Style 2 (the default) outputs a very readable form
which takes into account the length of hash keys (so the hash value lines
up). Style 3 is like style 2, but also annotates the elements of arrays
with their index (but the comment is on its own line, so array output
consumes twice the number of lines). Style 2 is the default.

Controls the degree to which the output can be evaled to recreate the supplied reference structures. Setting it to 1 will
output additional perl statements that will correctly recreate nested
references. The default is 0.

When set, enables the use of double quotes for representing string values.
Whitespace other than space will be represented as [\n\t\r], ``unsafe'' characters will be backslashed, and unprintable characters
will be output as quoted octal integers. Since setting this variable
imposes a performance penalty, the default is 0. The Dumpxs() method does not honor this flag yet.

When set, Data::Dumper will emit single, non-self-referential values as
atoms/terms rather than statements. This means that the $VARn names will be avoided where possible, but be advised that such output may
not always be parseable by eval.

Can be set to a method name, or to an empty string to disable the feature. Data::Dumper will invoke that method via the object before attempting to stringify it. This method can alter the contents of the object (if, for instance, it contains data allocated from
C), and even rebless it in a different package. The client is responsible for making sure the specified method can be called via the object, and that the object ends up containing only perl data types after the method has been called. Defaults to an empty string.

Can be set to a method name, or to an empty string to disable the feature.
Data::Dumper will emit a method call for any objects that are to be dumped
using the syntax blessMETHOD()>. Note that
this means that the method specified will have to perform any modifications
required on the object (like creating new state within it, and/or
reblessing it in a different package) and then return it. The client is
responsible for making sure the method can be called via the object, and
that it returns a valid object. Defaults to an empty string.

Can be set to a boolean value to control whether hash keys are quoted.
A false value will avoid quoting hash keys when it
looks like a simple string. Default is 1, which will always enclose hash
keys in quotes.

Can be set to a string that specifies an alternative to the bless
builtin operator used to create objects.
A function with the specified name should exist, and
should accept the same arguments as the builtin. Default is bless.

Run these code snippets to get a quick feel for the behavior of this
module. When you are through with these examples, you may want to add or
change the various configuration variables described above, to see their
behavior. (See the testsuite in the Data::Dumper distribution for more
examples.)

Due to limitations of Perl subroutine call semantics, you cannot pass an
array or hash. Prepend it with a \ to pass its reference instead. This will be remedied in time, with the
arrival of prototypes in later versions of Perl. For now, you need to use
the extended usage form, and prepend the name with a * to output it as a hash or array.

Data::Dumper cheats with
CODE references. If a code reference is encountered in the structure being processed, an anonymous subroutine that contains the string
'``DUMMY''' will be inserted in its place, and a warning will be printed if
Purity is set. You can eval the result, but bear in mind that the anonymous sub that gets created is just a placeholder. Someday, perl will have a switch to cache-on-demand the string representation of a compiled piece of code,
I hope. If you have prior knowledge of all the code refs that your data structures are likely to have, you can use the
Seen method to pre-seed the internal reference table and make the dumped output
point to them, instead. See EXAMPLES
above.

The Useqq flag is not honored by Dumpxs() (it always outputs strings in single quotes).

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other